Slide rule cursor



Jan. 31, 1967 F. MULLER ,301,480

SLIDE RULE CURSOR Filed Aug. 23, 1965 2 Sheets-Sheet l H wllllliilmauyflL 1mg;

IIIAVIVil INVENTOR d rr'aj r- F. MULLER Jan. 31, 1967 INVENTOR fiea rxyh United States Patent assignor Hamburg- The present invention relatesto a slide rule cursor comprising at least one transparent plate whichat two oppositely located substantially parallel edges is respectivelyprovided with guide bars. These guide bars have those sides thereofwhich face each other designed as guiding surfaces for engagement withthe slide rule, while one of said guide surfaces is equipped with springmeans for engagement with the slide rule.

Slide rule cursors of this type as heretofore known have said springmeans formed by a flat elongated metal tongue which is connected to oneof the guide bars. The assembly and connection of such metal springmeans to the respective guide bar necessitates a special operation andin addition thereto requires a certain amount of care in order to assurethat the marks on the curs-or will run parallel to those on thegraduated scale.

It is, therefore, an object of the present invention to provide a sliderule cursor in which the provision of the spring means on the respectiveguide bar will be greatly simplified.

It is another object of this invention to provide a slide rule cursor asset forth above, which will not require a special assembly operation forarranging the spring means on the respective guide bar.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawings, in which:

FIG. 1 is a transverse section through a slide rule cursor according tothe present invention. I

FIG. 2 is a top view of the slide rule cursor of FIG. 1,

however, with the upper reading window removed therei from.

FIG. 3 is a section along the line III-III of FIG. 1 but with the upperwindow mounted thereon.

The slide rule cursor according to the present invention ischaracterized primarily in that the spring means on the guide bars ofthe cursor do not represent separate elements connected to therespective guide bar by screws or other fastening means but form asingle integral piece with the respective guide bar. In other words,when the guide bar is produced the spring means is either worked out ofthe guide bar by a cutting operation or the like or the spring means issimultaneously molded with the respective guide bar. In this 'way, nospecial assembly and aligning operations are necessary for the springmeans thereby greatly simplifying the manufacture of the slide rulecursor. Moreover, there is no danger that the spring means get-s loosewith regard to the guide bar.

Referring now to the drawings in detail, the slide rule cursor showntherein is intended for two-sided slide rules. It is for this reasonthat the slide rule cursor, generally designated 10, has two readingwindows 11 and 12 held at the required distance from each other, inconformity with the thickness of the slide rule, by substantiallyparallel guide bars 13 and 14 at the side portions of the windows. Sincethe ends of two-sided slide rules are in the vast majority of casesprovided with cross bars, the cursor cannot be mounted on the slide ruleby slipping it on from one end. For this reason, slide rules of thistype are provided with means which permit the taking 011 of one of thereading windows. With the specific slide rule cursor according to thepresent invention, the reading window 12 is detachably connected toguide bar 14. To this end, guide bar 14 has at least one bore 19therethrough in which is arranged a collar-shaped resilient means 20. Incontrast to heretofore known arrangements of the type involved in whicha ring was provided with a slit and in-- jected into a bore, means 20 inbore 19 according to the present invention is formed merely by ametal-free collar-shaped constriction of relatively short axial length,which make-s it possible to detachably receive and lock a stud 23 in apush button-like manner, as shown in FIG. 3, according to which pushbutton 23 extends through a bore 12a in window 12 and has its lower end23b snapped in collar-shaped resilient means 20. The same type of snapfastener is employed at both ends of window 12 to connect it to both ofbars 13 and 14. The guide bar 14 is of the customary shape. In order toassure a precise support of the slide rule cursor along the sides of theslide rule, the ends only of guide bar 14 are designed as guidingsurfaces 22, whereas the adjacent surface area 21 between sliding andguiding surfaces 22 is recessed so as not to contact the slide rule whenthe cursor is mounted thereon. As will be seen from the drawing,especially FIG. 3, reading window 11 is connected to guide bars 13 and14 by means of screws 24 and 25 respectively engaging correspondinglythreaded bores 26 and 27 in the guide bars. FIG. 3 shows guide bar 14but guide bar 13 is identical thereto with respect to the fastening ofthe reading windows to the bars. According to a particularlyadvantageous embodiment of the present invention, one of the readingwindows may be made of one and the same piece with one of the guidebars, for instance, guide bar 14 so that no screw connection between thewindow 11 and the guide bar 13 is necessary.

In order to assure that the cursor be as evenly supported as possible onthe body of the slide rule, it is advisable to provide the cursor withspring means, generally designated 15, said spring means preferablycomprising two tongues 16, 16a having their free ends extending inopposite directions, i.e. in the approximate transverse direction of thecursor while being located slightly be neath the top and bottom surfacesof the guide bar 13. Tongues 16, 16a preferably extend from the centerportion of the guide bar 13 while confining with each other an obtuseangle. Preferably, the free ends of the tongues are provided withfoot-shaped surfaces located parallel to the direction of displacementof the cursor. The free ends of the resilient tongues extend slightlybeyond the adjacent external end surfaces of guide bar 13 in thedirection toward the guide bar 14.

The guide bars of the cursor may be of any suitable material which hasadequate anti-friction properties as for instance a plastic materialproduced by the polymerization of anhydrous formaldehyde with about 1500formaldehyde units to the molecule. Such a material is known, forinstance, under the trademark Delrin produced and marketed by Du Pont.Also material such as the material known under the trademark Teflon issuitable for the guide bars according to the invention.

The spring means 16, 16a may be molded simultaneously with and of thesame material as guide bar 13. However, if desired, the spring means 16,16a together with the guide bar 13 may first be molded as a single solidpiece whereupon slits 17 are machined into the thus It is, of course, tobe understood that the present invention is, by no means, limited to theparticular arrangement shown in the drawings but also comprises anymodifications within the scope of the appended claims.

-What I claim is:

1.v A slide rule cursor which includes: at least one transparent plateforming a sight window, first rail means arranged adjacent to one endface of said plate and provided with a guiding surf-ace for slidingengagement with one side surface of a slide rule, and second rail meansof polymer plastic material arranged adjacent to the other end face ofsaid plate opposite said first nail means so that one side of saidsecond rail means faces said first rail means, said second rail meanshaving a guiding surface at each end facing said firs-t rail means, saidsecond rail means having a slot extending from inwardly of each guidingsurface :laterally and at an angle to the surface toward the center ofsaid rail means, said slots defining tongues forming an obtuse anglebetween said guiding surfaces on the side of said second rail meansfacing said first rail means with their ends closer to said first railmeans than said guiding surfaces, so that said tongues will resilientlyengage the side of said rule under tension when 4, in position on saidrule, and a second plate fixed to the opposite sides of said rail means.

2. A slide rule according ,to claim 1, in which said second plate isdetachably secured to said rail means by a resilient snap fastener ateach end.

References Cited by the Examiner UNITED STATES PATENTS 1,021,484 3/1912Richardson 235- 2,173,459 9/1939 van Doormaal 235-70 2,334,725 11/1943Perkins 235 7o.2 2,486,748 11/1949 Koenig 235-70 2,968,438 l/l96lBachmann et al 23570.2 3,047,222 7/196'2 Kasmann 235 70.2 3,195,8137/1965 Hart 235 FOREIGN PATENTS 583,637 12/1946 GreatBritain.

RICHARD B. WILKINSON, Primary Examiner.

LOUIS J. CAPOZI, Exa'miner.

JAMES G. MURRAY, Assistant Examiner.

1. A SLIDE RULE CURSOR WHICH INCLUDES: AT LEAST ONE TRANSPARENT PLATEFORMING A SIGHT WINDOW, FIRST RAIL MEANS ARRANGED ADJACENT TO ONE ENDFACE OF SAID PLATE AND PROVIDED WITH A GUIDING SURFACE FOR SLIDINGENGAGEMENT WITH ONE SIDE SURFACE OF A SLIDE RULE, AND SECOND RAIL MEANSOF POLYMER PLASTIC MATERIAL ARRANGED ADJACENT TO THE OTHER END FACE OFSAID PLATE OPPOSITE SAID FIRST RAIL MEANS SO THAT ONE SIDE OF SAIDSECOND RAIL MEANS FACES SAID FIRST RAIL MEANS, SAID SECOND RAIL MEANSHAVING A GUIDING SURFACE AT EACH END FACING SAID FIRST RAIL MEANS, SAIDSECOND RAIL MEANS HAVING A SLOT EXTENDING FROM INWARDLY OF EACH GUIDINGSURFACE LATERALLY AND AT AN ANGLE TO THE SURFACE TOWARD THE CENTER OFSAID RAIL MEANS, SAID SLOTS DEFINING TONGUES FORMING AN OBTUSE ANGLEBETWEEN SAID GUIDING SURFACES ON THE SIDE OF SAID SECOND RAIL MEANSFACING SAID FIRST RAIL MEANS WITH THEIR ENDS CLOSER TO SAID FIRST RAILMEANS THAN SAID GUIDING SURFACES, SO THAT SAID TONGUES WILL RESILIENTLYENGAGE THE SIDE OF SAID RULE UNDER TENSION WHEN IN POSITION ON SAIDRULE, AND A SECOND PLATE FIXED TO THE OPPOSITE SIDES OF SAID RAIL MEANS.